Sinusitis is a condition affecting over 35 million Americans, and similarly large populations in the rest of the developed world. Sinusitis occurs when one or more of the four paired sinus cavities (i.e., maxillary, ethmoid, frontal, sphenoid) becomes obstructed. Normally the sinus cavities, each of which are lined by mucosa, produce mucous which is then moved by beating cilia from the sinus cavity out to the nasal cavity and down the throat. The combined sinuses produce approximately one liter of mucous daily, so the effective transport of this mucous is important to sinus health.
Each sinus cavity has an opening into the nasal passage called an ostium. When the mucosa of one or more of the ostia or regions near the ostia become inflamed, the egress of mucous is interrupted, setting the stage for an infection of the sinus cavity, i.e., sinusitis. Infections of the maxillary and/or ethmoid sinuses make up the vast majority of cases of sinusitis, with far fewer cases involving the sphenoids and frontals.
Unlike the maxillary, frontal, and sphenoid sinuses, the ethmoid sinuses are comprised of several individual air cells, each of which has a relatively small drainage path and ostium for drainage into the nasal cavity. The ethmoid sinuses are grouped into anterior and posterior air cells. The anterior air cells are anterior to the basal lamella of the middle turbinate while the posterior air cells are posterior to the basal lamella. From a sinusitis standpoint, the anterior air cells are usually isolated from the posterior air cells, and more commonly involved with sinusitis.
It is estimated that about 25-30% of sinus disease is confined to the maxillary sinuses. Another 20-30% of sinus disease, however, further involves the anterior ethmoid sinus air cells, the largest (and most commonly involved) of which is typically the ethmoid bulla. Currently, the surgical treatment of disease of the ethmoids is accomplished by ethmoidectomy during functional endoscopic sinus surgery (FESS). In this process, the walls of the air cells are essentially completely removed to their lateral aspect, essentially eliminating them. While this procedure is relatively simple for a surgeon, the patient is almost always under general anesthesia. Furthermore, there is a significant amount of post-surgery pain during recovery for the patient when ethmoidectomy (and any additional surgery done during FESS) is performed. There thus is a need for less invasive ways to treat diseased ethmoid sinuses.
While it is potentially possible to address disease of the involved ethmoid air cells less invasively by improving their natural drainage, such as by balloon dilation, the location of the individual ostia are quite variable, and they are difficult to find with any currently available visualization techniques. While a certain percentage of patients in whom some or all of their anterior ethmoid air cells are diseased, in addition to their maxillary sinuses and associated osteo meatal units (OMU) including their ostia and infundibular spaces, treatment of only their OMU by dilation of the maxillary ostia and remodeling of the uncinate process may also resolve any disease of the anterior ethmoid air cells. However, in some patients with both anterior ethmoid and maxillary disease, it may be necessary to directly intervene on one or more of the anterior air cells, such as the ethmoid bulla. Ideally such an intervention would be minimally invasive, and could be performed under local anesthesia, without requiring general anesthesia. Such a procedure, in addition to the previously described dilation treatments for other sinuses such as maxillary, frontal, and sphenoid, has the potential to be performed in a physician's office or on an outpatient basis. This would be especially true if the procedure could be performed using endoscopic techniques.
For these and other reasons, there is a clear need for better methods and devices for the treatment of diseased ethmoid sinuses.